1. Field of the Invention
This invention relates to color cathode ray picture tubes and is addressed particularly to an improved anode connector assembly for the introduction of a high voltage potential into the envelope of such tubes.
A high voltage potential is required for operation of the CRT electron gun and for energizing the screen of the tube. The potential is in the range of twenty to fifty-five kilovolts, with the magnitude of the voltage dependent upon the size and type of tube. The voltage is routed into the tube envelope through what is commonly termed an "anode cup," which comprises a hollow, tapered cup-shaped member sealed into the side wall of the tube funnel, and which has an annular lip for receiving latching means of the anode connector assemble. The anode cup is in contact with an electrically conductive coating on the inside wall of the funnel. The high potential is conducted through a conductive coating on the internal surface of the funnel to the final, accelerating anode of the electron gun located in the neck of the tube, and to the screen of the tube located adjacent to the faceplate.
Connection of the high-voltage to the anode cup is typically made by means of an anode connector assembly. The assembly comprises a disc-shaped, flexible rubber cap from which extend latching means that connect to the anode cup. An electrical conductor that receives voltage from an associated high-voltage supply is routed into the rubber cap and is electrically and mechanically joined with the latching means.
An anode connector assembly must fulfill certain basic requirements. It must be able to conduct and isolate high voltage. The higher the voltage, the more difficult it is to constrain as it tends to "track," that is, to form a parasitic path to a nearby electrical conductor such as the coating on the outside surface of the funnel which is at ground potential. The outer conductive coating, in conjunction with the inner conductive coating, serves as a capacitor in the high-voltage supply circuit.
The anode connector must provide a shield against x-ray emission. X-rays generated by tube are normally confined to the interior of the tube by the presence of the element lead in the glass of the tube envelope. The anode cup however provides a channel for escape of x-rays, and the anode connector assembly must provide supplementary X-ray shielding.
An anode connector assembly known in the art has latching means has a base from which extend hooks for latching onto an anode cup. A metal flap extends from the base, with a hole in the flap for receiving the bared wire of a high-voltage conductor. A second component comprises a circular plate with an internal aperture for passing the hooks. When the plate is forced into a cavity in the anode cap and against the flap, the flap folds down over the bare wire to make electrical and mechanical connection. The assembly relies upon the resilience of the flexible anode cap to make the proper mechanical and electrical connection with the high-voltage conductor.
2. Other Prior Art
U.S. Pat. Nos. 4,204,741 and 4,894,023 to Hall.